The present invention is directed to an apparatus and method for forming a proteinaceous emulsion or batter into shaped food products such as sausages, and more particularly to a method of stuffing and an apparatus including a stuffing tube slideably received in a mold tube.
Sausages and other formed meat products such as bologna, Vienna sausages, and the like typically are made by extruding a proteinaceous meat emulsion or batter into an artificial casing of a desired size and shape, and then cooking the batter within the casing. After cooking, the casing is peeled from the meat product and discarded. Once the casing has been removed, the shaped meat product can be cut into predetermined lengths and placed in suitable containers for distribution to consumers.
Various devices and methods for making casingless sausages have been proposed in order to form and process sausages and the like without the use of casings, which are undesirable because of added costs resulting from the requirements of providing casings and thereafter disposing of the used casings. Examples are U.S. Pat. Nos. 5,056,425 and 5,118,519 to Mally. The Mally patents disclose an apparatus which ejects partially shaped products onto a conveyor assembly. According to Mally, batter is pumped into a molding tube, and a treating assembly is formed as a continuation of the molding tube. The treating assembly functions to introduce treating fluid, typically a food grade acid solution, which causes a proteinaceous skin to form about the batter. A piston or ram mechanism causes the batter with proteinaceous skin to be deposited onto a conveyor belt. The conveyor belt then continues into a cooking apparatus. Once cooked, the product is canned.
U.S. Pat. No. 3,885,053 to Townshend discloses a process of forming a skin on an extruded meat emulsion by applying an acid to the surface of the emulsion as the extrusion proceeds. Acid is pumped from an outside source into a conduit into which emulsion is extruded, where acid treatment, emulsion flow, and subsequent treatments all occur in a single conduit. Accordingly, while the device in Townshend can be used in a stand-alone procedure, it is not suitable for a high output production process.
U.S. Ser. No. 09/690,358 (hereinafter xe2x80x9c""358 applicationxe2x80x9d), filed on Oct. 17, 2000, and with a corresponding PCT application being published under Publication No. WO 01/30164, is directed to an apparatus and method for forming casingless sausages. The ""358 application and its PCT application are commonly owned with the present invention. The ""358 application describes a molding tube that is slideably mounted about a stuffing tube, the stuffing tube comprising concentric inner and outer tubes. Emulsion is pumped through the inner tube of the stuffing tube and forced against the closed end of the molding tube, causing the molding tube to move relative the stuffing tube. The ""358 application describes a stuffing tube with both inner and outer tubes, where the treating fluid flows in an annular passage between these tubes and is then released into the molding tube.
According to the ""358 application, the treating fluid deposition should be continuous so as to evenly coat the inside of the molding tube, thereby forming a proteinaceous skin about the surface of the emulsion. However, the ""358 application does not address controlling the relative amounts of emulsion and treating fluid which flow into the molding tube.
It would be desirable to provide an apparatus and method for forming a casingless food product of the type having telescoped stuffing and mold tubes, wherein a single stuffing tube is capable of making simultaneous depositions of emulsion and treating fluid, wherein the relative amounts of emulsion and treating fluid which flow into the mold tube are controlled and there is substantially no relative motion between the emulsion and treating fluid.
The present invention relates to an apparatus and methods for forming a proteinaceous emulsion or batter into shaped food products such as sausages without the use of a casing. In one exemplary embodiment, a supply of suitable proteinaceous emulsion is provided, and the emulsion is conveyed under pressure through an elongated hollow stuffing tube into a mold tube, where the stuffing tube is slideably mounted co-axially within the mold tube, and treating fluid is conducted through a conduit formed in the stuffing tube wall. According to one method of the present invention, the stuffing tube is fully inserted into the mold tube and then retracted as emulsion exits the stuffing tube. Preferably, the mold tube and stuffing tube move axially apart at such a rate that the emulsion substantially fills the mold tube but essentially does not slide on the walls of the mold tube.
As the emulsion exits the stuffing tube and enters the mold tube, the treating fluid forms a skin over the surface of the emulsion, such that the treating fluid evenly coats the emulsion being deposited in the mold tube. The treating fluid is directed to the interior surface of the mold tube in such a manner that the interior surface of the mold tube is continuously wetted by the treating fluid, as the mold tube moves relative to the stuffing tube. Depositions of emulsion and treating fluid occur substantially without relative motion between the emulsion and the treating fluid, or between the emulsion/treating fluid and the interior surface of the mold tube. This ensures that the entire outer surface of the molded emulsion is contacted by the treating fluid, thereby forming a coagulated proteinaceous skin on the molded emulsion and, hence, preventing the emulsion from adhering to the interior surface of the mold tube to any significant degree.
Preferred treating fluids include diluted food grade acids, including but not limited to the following: acetic acid, ascorbic acid, citric acid, fumaric acid, malic acid, hydrocholoric acid, and phosphoric acid. Any suitable acidic material having some lubricating properties and being capable of reacting with the proteinaceous skin on the molded emulsion to form a coagulated, cohesive skin surface is suitable. Both organic and inorganic acid materials can be used as the treating fluid.
Preferably there is provided a smooth, steady deposition of emulsion from the stuffing tube that is received within a thin coating of treating fluid on the mold tube surface, the emulsion deposition occurring substantially without folds, ripples, or sticking spots on the emulsion product. The present invention provides that depositions of treating fluid and emulsion occur substantially without relative motion between the treating fluid and emulsion, meaning that the emulsion does not slide on the mold tube wall to any significant degree, the mold tube remains free and clear of emulsion residue, and product having the desired surface characteristics can be easily ejected from the mold tube after subsequent thermal treatment.
After the mold tube is filled with emulsion and the stuffing tube is fully retracted, the mold tube is separated from the stuffing tube. The mold tube with molded emulsion product inside is then subjected to a heat treatment to cook the emulsion. A length of formed product (e.g. sausage) can be removed from the mold tube for further processing. The product can be formed to any desired length or shape, subject only to limitations in the type of equipment used. Times for heat treating different types of molded emulsion product are well known to those of ordinary skill in the food processing arts.
Preferably, there is an approximately constant ratio of treating fluid to emulsion in the mold tube. Typically, the amount of treating fluid is quite small compared to the amount of emulsion, and preferably the ratio thereof is set at a predetermined level. The relative axial velocities of the stuffing and mold tube can be set, i.e., a retraction rate of the stuffing tube from the mold tube can be fixed at a desired level. The volume flows of the emulsion and treating fluid must be closely regulated and synchronized with the relative axial motion between the stuffing tube and mold tube to assure that the treating fluid evenly coats the emulsion resident in the mold tube as the stuffing tube withdraws. Mechanisms and methods for determining and controlling relative velocities are well known in the art.
The time required to fill the mold tube is relatively short compared to the time for thermal treatment. Therefore, a single stuffing tube can be operated in conjunction with a much larger number of mold tubes. For example, a rotary arrangement can be provided with multiple sets of mold tubes for every one set of stuffing tubes. After a stuffing operation, the mold tubes preferably are held in heat treatment for a predetermined interval. The mold tubes and stuffing tubes can be arranged in a sequential, repetitive production process.
Based on the above-described methods, various mechanical configurations can be designed either to produce single pieces of product, such as sausage, on demand, or to produce a high rate of continuous product, e.g., by using automated equipment.
The herein described invention is directed to an apparatus for forming a casingless food product including a stuffing tube extending between an input end and a discharge end, the stuffing tube having a wall defining a central emulsion passage, a treating fluid passage positioned within the wall of the stuffing tube and radially outside of the central emulsion passage, and further including a mold tube for receiving the stuffing tube, the stuffing tube being slideable axially along the mold tube, wherein depositions of emulsion and treating fluid are made from the discharge end of the stuffing tube into the mold tube. Preferably, such depositions occur substantially without relative motion between the emulsion and the treating fluid.
A method according to the present invention is characterized by providing emulsion and treating fluid conveyed through a stuffing tube, the stuffing tube having a wall defining a central emulsion passage, and a treating fluid passage positioned within the wall and radially outside of the central emulsion passage; receiving the stuffing tube in a mold tube, the stuffing tube being slideable along the mold tube; depositing the emulsion from the central emulsion passage into the mold tube through a discharge end of the stuffing tube; and depositing the treating fluid from the treating fluid passage into the mold tube through the discharge end of the stuffing tube. Preferably the depositing steps occur substantially without relative motion between the emulsion and the treating fluid.
Additional optionally present parameters of the invention include providing a sliding seal positioned around the periphery of the stuffing tube, wherein the sliding seal can be an elastomer or a polymer. The mold tube preferably includes an output end having a valve member rotatable between an open and a closed position, wherein in the open position the valve member permits the food product to exit the mold tube, and in the closed position the valve member blocks the output end of the mold tube. Preferably the valve member forms a seal with the mold tube and is made of a polymer. The valve member also can include a valve support to counterbalance a pressure force in the mold tube, wherein the valve support can include a chamber within the valve support for receiving fluid to pressurize the valve support.
Further optional parameters of the invention include a central emulsion passage which is narrowed in a region for receiving the sliding seal. The central emulsion passage also can include a region of expanding surface area near its discharge end.
Preferably the treating fluid passage includes a conduit positioned within the wall of the stuffing tube that runs generally parallel to the central emulsion passage. The treating fluid passage also can include a circumferential groove for distributing the treating fluid through the discharge end of the stuffing tube. A guide ring can be positioned circumferentially around the stuffing tube in order to maintain a clearance between the stuffing tube and the mold tube. The guide ring can contain a plurality of grooves to distribute the treating fluid into the mold tube.
The apparatus can further include an emulsion pump for pumping emulsion from a delivery vessel to the stuffing tube, and a treating fluid pump for pumping treating fluid into the stuffing tube. A jacket can be provided to surround the mold tube for circulating hot or cold fluid. Preferably both the stuffing tube and the mold tube are made of stainless steel or a similar material of sufficient strength and wearability.
A production machine incorporating one or more of the above features can include an array of stuffing tubes and an array of mold tubes, where the mold tubes can be positioned in rows on a rotary wheel.
Further aspects of an exemplary method according to the present invention include a step of inserting the stuffing tube into the mold tube prior to depositing the emulsion and treating fluid. The stuffing tube preferably is retracted from the mold tube during the depositing steps. Accordingly, flow rates of emulsion and treating fluid are controlled, and can be provided in a fixed ratio. Further, the rate of retraction of the stuffing tube can be controlled, and can be linked in a constant ratio with the treating fluid flow rate. Additional steps of the method include heat treating the emulsion and treating fluid in the mold tube, and then opening an exit valve after heat treating to release the molded food product.
Other aspects and examples of the invention are more fully discussed below.